1. Field of the Invention
This invention relates to a needle shield/needle guard device for a hypodermic syringe with a needle that is permanently attached to the forward end of the syringe barrel. This needle shield/needle guard device is positively locked to the syringe barrel and can perform two functions: (1) in the untampered state, it can function as a needle shield to enclose and prevent contamination of a sterile needle that is permanently attached to the forward end of the syringe barrel and, (2) after an aperture has been created by pulling off a tab on the front end of the device, it can function as a needle guard which permits the operator to uncover and re-cover a needle by retracting or extending the device on the syringe barrel from behind the needle point. The operator of this device can avoid direct contact with the needle point and thus reduce accidental puncture with used needles, which could transmit blood-borne infections such as AIDS, hepatitis, syphilis, and other infectious illnesses.
2. Description of the Prior Art
There are several major problems inherent in the design of existing needle shields which must be removed from needle hubs before a syringe needle can be used for a medical procedure. Examples of these removeable needle shields include the following references selected from the U.S. Patent and Trademark Office: U.S. Pat. Nos. 3,381,813; 3,934,722; 4,113,090; and 4,121,588. These removeable needle shields reveal several limitations such as: (1) after a liquid medicament has been drawn up in a syringe, medical personnel may occasionally delay the administration of the medicament, which would require replacement of a needle shield back over the needle to prevent contamination of the sterile needle. This maneuver requires keeping track of the removed needle shield and then replacing the needle shield back over the needle, which represent extra steps for busy medical personnel; (2) another common practice occurs when medical personnel remove this type of needle shield by holding the needle shield between their teeth or lips. This maneuver has been associated with accidental self-puncture in the face or other bodily parts; (3) in order to re-cover a used needle with a previously removed needle shield, it is necessary to replace the needle shield back over the pointed end of the used needle, which increases the risk to medical personnel who may accidentally puncture themselves with the pointed end of the used needle; (4) when the needle shield is replaced over the used needle, if the needle has been accidentally bent during a medical procedure or if the needle shield is replaced over the needle at an incorrect angle, the needle point may inadvertently pierce the side of the needle shield as it is being replaced over the needle. The operator using the needle shield could be punctured with a used needle point that has exteriorized through a needle shield; and (5) most medical facilities use storage containers with or without a clip-off needle device to store used needles. Personnel may puncture themselves with used, uncovered needles that may accidentally fall out of these storage containers or with uncovered needles that are disposed of inappropriately in wastebackets. In addition, if the storage container is full, it is possible to accidentally puncture oneself with a used, uncovered needle that is pointed towards the opening of the waste container.
Other devices relevant to the field of our invention are known and the following patents listed in the U.S. Patent and Trademark Office exhibit certain differences and/or limitations in comparison to our invention.
U.S. Pat. No. 4,425,120 issued to Sampson et al describes a needle guard device which is attached to a syringe barrel and functions to uncover or re-cover a needle. In this patent, in order to remove the detachable needle from the syringe barrel, it is necessary to recover the used needle with a separate needle shield, which increases the risk of puncture with a used needle point. In addition, this needle guard has an open-end, which precludes its use to function also as a needle shield to enclose and prevent contamination of a sterile needle. In order to prevent contamination of the sterile needle in this device, it would be necessary to cover the needle with a separate needle shield, or close the opening of the needle guard with a material which must be ruptured by the needle or needle shield enclosing the needle.
U.S. Pat. No. 4,139,009 issued to Alvarez is composed of four longitudinal arms which are brought into lateral side-to-side contact with the intention of covering and protecting the enclosed needle. The front end of the cover and the lateral arms in side-to-side contact represent discontinuous locations which could permit microorganism penetration and contamination of the enclosed sterile needle. In addition, the arms in their normal unstressed condition are slightly bowed away from the longitudinal axis of the needle, so that casual touching of the device could contaminate the needle through the open interspaces between the separated arms. When this device is pushed against a skin surface during the injection process, the arms must bow away from the longitudinal axis of the needle which could block visualization of the needle as it penetrates the skin. There are several medical indications in which the operator must observe the penetration of the needle into the skin in order o avoid a blood vessel or conversely, if the operator is attempting to withdraw blood it is important to be able to clearly visualize a blood vessel.